1. Field of the Invention
The invention relates to a civil engineering machine for spreading material for spreading on soils or base materials and in particular to a civil engineering machine for spreading binders for stabilising the soil or base material. The invention relates in this case both to a civil engineering machine which is intended solely for discharging the binder and to a civil engineering machine which has a milling or mixing rotor by which, directly after the discharge, the binder can be mixed into the soil or base material which has been milled up.
2. Description of the Prior Art
To improve or consolidate soils or base materials, it is known for binders to be introduced into them to improve their ability to be laid and their load-bearing capacity. Typical applications for soil or base material stabilization are the construction of roads, railways and surfaces for industrial use.
The known stabilizers or recyclers have a storage container for a dry binder, such as lime or cement for example, and a spreader mechanism for discharging the binders onto the soil or base material and a milling or mixing rotor by which the soil or base material can be milled up and the binder can be mixed into the soil or base material immediately after it has been discharged. What is generally mixed into the soil or base material in this case is a binder in powder form. As well as recyclers or stabilizers, what are also known are civil engineering machines by which the binder can only be applied to the soil or base material and cannot be mixed into it. These civil engineering machines are also referred to as binder spreaders.
The known binder spreaders have a storage container and a spreading mechanism for discharging the binder onto the soil or base material. Self-propelled and non-self-propelled binder spreaders are known. The non-self-propelled binder spreaders are mounted on a drawing vehicle, and in particular on a tractor, or are towed by the tractor. The self-propelled binder spreaders have a chassis which is carried by wheeled running gear and a drive unit for the wheels.
When binders in powder form are being spread, the problem arises that dust is produced. The known civil engineering machines therefore have an anti-dust arrangement in the form of a skirt which surrounds the outlet of the spreading mechanism on all sides.
In practice it has been found that the anti-dust arrangement of the known civil engineering machines is not always sufficiently good to stop dust from being produced to an adequate degree. Particularly in fairly high winds, it may happen that the binder is blown away as it emerges from the outlet of the spreading mechanism, in spite of the anti-dust arrangement.
U.S. Pat. No. 4,990,025 describes a stabilizer for mounting on a tractor. This known stabilizer has a milling or tilling and mixing rotor which is arranged in a rotor housing which comprises an injection arrangement for injecting a liquid binder. The problem of dust being produced cannot arise with a stabilizer having an injection arrangement because the material which is milled or tilled up has a liquid binder injected into it in the rotor housing.
A stabilizer or recycler which has a built-in arrangement for spreader binders in powder form is known from EP 1 012 396 B1. The binder is made available in a funnel-shaped supply container at the bottom end of which is arranged a rotary feeder by which the binder can be dispensed in a metered fashion. Provided below the rotary feeder are flexible sealing-off walls such for example as rubber flaps which surround a spreading compartment which is open at the end to the rear in the direction of travel and into which the binder is dropped. Immediately after the discharge of the binder, the milling or mixing rotor of the stabilizer or recycler travels over it and mixes it with the soil or base material which has been milled up.